His work suggests that Australia's all-ages bicycle helmet laws incur a health cost to the nation of more than a half a billion dollars [AUD] every year. In other words, there is now evidence that bicycle helmet laws have a direct, negative impact on Australian health costs. They amount to $301 million a year and a total cost of $519 million when combined with the non-health costs of the law.

The model's mathematical formula uses various inputs, including the exercise benefits of cycling, head injury percentages and reductions in cycling popularity due to helmet laws.

Professor de Jong has a spreadsheet with which his formula can be calculated using inputs from other regions. It's available online and if you know the stats for your country, you can do your own calculations.

He has further calculated that if America adopted nationwide helmet laws like those in Australia, the USA would suffer a health cost of $4.75 billion every year.

In Great Britain, nationwide all-age helmet laws would result in a health cost of $400 million per year and the Netherlands would be incredibly hard hit and suffer a $1.9 billion annual loss.

Here's the abstract for the paper:

A model is developed which permits the quantitative evaluation of the benefit of bicycle helmet laws. The efficacy of the law is evaluated in terms of the percentage drop in bicycling, the percentage increase in the cost of an accident when not wearing a helmet, and a quantity here called the "bicycling beta." The approach balances the health benefits of increased safety against the health costs due to decreased cycling.

Using estimates suggested in the literature of the health benefits of cycling, accident rates and reductions in cycling, suggest helmets laws are counterproductive in terms of net health. The model serves to focus the bicycle helmet law debate on overall health as function of key parameters: cycle use, accident rates, helmet protection rates, exercise and environmental benefits.

Empirical estimates using US data suggests the strictly health impact of a US wide helmet law would cost around \$5 billion per annum. In the UK and The Netherlands the net health costs are estimated to be \$0.4 and \$1.9 billion, respectively.

Kilometres cycled by Copenhageners so far today

Copenhagenize.com is the blog of Copenhagenize Design Company. Online since 2007 and highlighting the cycling life in Copenhagen and around the world.

40 years ago Copenhagen was just as car-clogged as anywhere else but now 41% of the population arriving at work or education do so on bicycles, from all over the Metro area. 56% of Copenhageners themselves use bicycles each day. They all use over 1000 km of bicycle lanes in Greater Copenhagen for their journeys. Copenhagenizing is possible anywhere.